Edward Snowden says he'd like to return to the U.S. - on one condition.

That's what the former National Security Agency contractor told CBS News in an interview that aired Monday on "CBS This Morning." Snowden has been living in exile in Russia since leaking classified information about the government's mass surveillance of U.S. citizens in 2013.

"I would like to return to the United States," Snowden told CBS. "That is the ultimate goal. But if I'm gonna spend the rest of my life in prison, the one bottom line demand that we have to agree to is that at least I get a fair trial. And that is the one thing the government has refused to guarantee because they won't provide access to what's called a public interest defense."

That type of defense would allow a jury to consider Snowden's motivations, which he says the government opposes.

"It's not hard to make the argument that I broke the law," he admitted to CBS, but said the government has not shown how his leaks caused harm. "They never show evidence for it even though we're now more than six years on, it would be the easiest thing in the world to show."

Earlier this year, the Wall Street Journal reported that the NSA was considering shutting down the once-secret surveillance program that he exposed because it lacks operational value.

Snowden, now a privacy advocate, added that he was alarmed by how governments and companies can now access vast amounts of personal data through digital devices such as cell phones.

"Anything you can do on that device, the attacker - in this case, the government - can do," Snowden told MSNBC. "They can read your e-mail, they can collect every document, they can look at your contact book, they can turn the location services on."

"They can see anything that is on that phone instantly," he said, "and send it back home to the mothership."

Not coincidentally, Snowden has a new memoir, "Permanent Record," coming out Tuesday.